CN212300381U - Fiber grating sensing demodulation device based on frequency shift interference fiber ring-down - Google Patents
Fiber grating sensing demodulation device based on frequency shift interference fiber ring-down Download PDFInfo
- Publication number
- CN212300381U CN212300381U CN202020859790.XU CN202020859790U CN212300381U CN 212300381 U CN212300381 U CN 212300381U CN 202020859790 U CN202020859790 U CN 202020859790U CN 212300381 U CN212300381 U CN 212300381U
- Authority
- CN
- China
- Prior art keywords
- optical fiber
- ring
- acousto
- optic modulator
- fiber grating
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Images
Abstract
The utility model discloses a fiber grating sensing demodulating equipment based on frequency shift interference optical fiber ring-down swings, including tunable laser of C wave band, optic fibre circulator, light splitting ratio be 50: 50 of a first optical fiber coupler, a first light polarization controller, an optical fiber ring-down ring, an asymmetrically inserted acousto-optic modulator, an acousto-optic modulator driving source, a balance detector, a data acquisition card and a computer; the utility model discloses insert optic fibre with fiber grating as sensing element and ring down, adjust the wavelength of continuous laser and make it be located fiber grating's linear work area intra-area. Because fiber grating's transmission intensity is linear variation along with external parameter's change to lead to optic fibre to ring down the total loss of ring and ring down the distance and change, consequently the utility model discloses the device can be applied to the change that acquires fiber grating and locate external parameter. The utility model discloses simple structure, it is with low costs, and have higher precision, sensitivity and stability.
Description
Technical Field
The utility model relates to a fiber grating sensing demodulation device, in particular to fiber grating sensing demodulation device based on frequency shift interference optical fiber ring-down swings.
Background
The fiber grating has the advantages of small volume, full compatibility with optical fibers, small additional loss, insensitive polarization, electromagnetic interference resistance, corrosion resistance, fast response, sensitivity of resonance wavelength to external parameters such as temperature, strain, refractive index and the like, easiness in networking, easiness in large-scale production and the like, and has been widely applied to the fields of civil engineering, aerospace, petrochemical industry, biomedicine, power system detection and the like.
The parameter to be measured can cause the drift of the central wavelength of the fiber grating, but the traditional wavelength demodulation method is limited by a spectrum analyzer and the resolution ratio thereof, the price is high, and the demodulation precision is low. In recent years, some reports of adopting the traditional fiber cavity ring-down spectroscopy technology to realize fiber grating sensing demodulation have appeared, so that the measurement precision and the sensitivity are improved, but the technology adopts pulse light, and a pulse laser or an electro-optical modulator is required to perform pulse modulation on a light source. Meanwhile, in order to process ring-down pulse signals, a fast photoelectric detector and high-speed data acquisition equipment are required, and the requirements on electronic components cannot be reduced, so that the system structure is difficult to simplify, the system cost is difficult to further reduce, and the practical application is greatly limited.
Disclosure of Invention
The utility model aims at providing a fiber grating sensing demodulating equipment based on frequency shift interference optical fiber ring-down swings, the device not only can avoid wavelength demodulation and use expensive spectral analysis appearance, and the light source adopts continuous light moreover, does not need pulse modulation, short-term test and high-speed demodulation, has with low costs, sensitivity height and the high advantage of measurement accuracy.
The utility model discloses fiber grating sensing demodulating equipment based on frequency shift interference optical fiber ring-down swings, including C wave band tunable laser, optic fibre circulator, beam split ratio for 50: 50 of a first optical fiber coupler, a first light polarization controller, an optical fiber ring-down ring, an asymmetrically inserted acousto-optic modulator, an acousto-optic modulator driving source, a balance detector, a data acquisition card and a computer;
the optical fiber ring-down ring is a closed ring formed by sequentially connecting a second optical fiber coupler, a delay optical fiber, a second light polarization controller, a third optical fiber coupler and an optical fiber grating; the second optical fiber coupler and the third optical fiber coupler have the same splitting ratio, and the splitting ratio is not less than 99: 1; the reflectivity of the fiber grating is not more than 10%;
the output end of the C-band tunable laser is connected with a first port of the optical fiber circulator, a second port of the optical fiber circulator is connected with a first input port of the first optical fiber coupler, and a third port of the optical fiber circulator is connected with the balance detector; the second input port of the first optical fiber coupler is connected with the balance detector;
the first output port of the first optical fiber coupler is connected with the first optical polarization controller, and the second output port of the first optical fiber coupler is connected with the acousto-optic modulator; the first optical polarization controller is connected with an input port of a second optical fiber coupler in the optical fiber ring-down ring, and the acousto-optic modulator is connected with an input port of a third optical fiber coupler in the optical fiber ring-down ring;
the output end of the balance detector is connected with the data acquisition card; one end of the acousto-optic modulator driving source is connected with the acousto-optic modulator, the other end of the acousto-optic modulator driving source is connected with the computer, and the data acquisition card is connected with the computer.
It should be noted that the first port, the second port, and the third port of the optical fiber circulator correspond to the ports (i), (ii), and (iii) of the optical fiber circulator shown in fig. 1, respectively. The first input port and the second input port of the first optical fiber coupler respectively correspond to the input port (i) and the input port (ii) of the first optical fiber coupler shown in fig. 1 (i.e., the ports marked on the left side of the first optical fiber coupler in fig. 1), and the first output port and the second output port of the first optical fiber coupler respectively correspond to the output port (i) and the output port (i.e., the ports marked on the right side of the first optical fiber coupler in fig. 1). The input port of the second fiber coupler corresponds to the port of the second fiber coupler shown in fig. 1, and the input port of the third fiber coupler corresponds to the port of the third fiber coupler shown in fig. 1. The port of the second optical fiber coupler is connected with the first optical polarization controller, and the port of the second optical fiber coupler is connected with the fiber bragg grating; the port II of the third optical fiber coupler is connected with the acousto-optic modulator, and the port I of the third optical fiber coupler is connected with the optical fiber grating.
The utility model discloses in, asymmetric inserted acoustic optical modulator indicates: the distances from the acousto-optic modulator to the output ports (first and second) of the first optical fiber coupler are different. Only when the acousto-optic modulator is inserted into a loop formed by two output ends of the first optical fiber coupler asymmetrically, two beams rotating clockwise and anticlockwise can be subjected to frequency shift for different time periods, and phase difference can be generated, so that interference is formed.
Further, the C-band tunable laser is a Santec TSL-510C model tunable laser.
Furthermore, the Fiber circulator, the first optical polarization controller and the second optical polarization controller all adopt single mode fibers of MC Fiber Optics company.
Furthermore, the first optical Fiber coupler, the second optical Fiber coupler and the third optical Fiber coupler are all optical Fiber couplers of MC Fiber Optics company.
Furthermore, the acousto-optic modulator adopts Brimrose AMM-100-20-25-1550-2FP model acousto-optic modulator.
Furthermore, the acousto-optic modulator driving source adopts a VFF-100-20-SPF-A-C2-X type driving source.
Further, the balanced detector employs a new fox model 2117.
Furthermore, the data acquisition card adopts an NI USB-6361 DAQ module.
Fiber grating is all more sensitive to external parameters such as temperature, pressure, strain, refracting index, so the utility model discloses insert optic fibre as sensing element with fiber grating and ring down, adjust the wavelength of continuous laser and make it be located fiber grating's linear work area. Because fiber grating's transmission intensity is linear variation along with external parameter's change to lead to optic fibre to ring down the total loss of ring and ring down the distance and change, consequently the utility model discloses the device can be applied to the change that acquires fiber grating and locate external parameter.
Compared with the prior art, the utility model discloses fiber grating sensing demodulation device has following advantage and beneficial effect:
(1) the frequency-shift interference optical fiber ring-down technology is adopted, an expensive spectrometer, a pulse laser or an electro-optical modulator and a quick electronic device are not needed, and therefore the frequency-shift interference optical fiber ring-down technology has the advantages of simple structure and low cost;
(2) meanwhile, frequency shift interference and differential detection are adopted, so that external interference can be eliminated, and higher precision and stability are achieved;
(3) the frequency shift interference and the optical fiber ring-down ring are combined, and the effect of external parameters on the optical fiber grating is amplified by utilizing the repeated cyclic attenuation of continuous laser in the optical fiber ring-down ring, so that the sensitivity of the optical fiber grating sensing demodulation can be greatly improved.
Drawings
Fig. 1 is a block diagram of the fiber grating sensing demodulation device of the present invention;
fig. 2 is a schematic diagram of the position of the laser wavelength in the transmission spectrum of the fiber grating.
In the figure, a 1-C waveband tunable laser, a 2-optical fiber circulator, a 3-first optical fiber coupler, a 4-first optical polarization controller, a 5-optical fiber ring-down ring, a 5-1-second optical fiber coupler, a 5-2-delay optical fiber, a 5-3-second optical polarization controller, a 5-4-third optical fiber coupler, a 5-5-optical fiber grating, a 6-acousto-optic modulator, a 7-acousto-optic modulator driving source, an 8-balance detector, a 9-data acquisition card and a 10-computer are arranged in the system.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more clearly understood, the following description of the embodiments of the present invention with reference to the accompanying drawings is provided. It should be understood that the detailed description and specific examples, while indicating the invention, are given by way of illustration only.
Examples
Referring to fig. 1, the fiber grating sensing and demodulating apparatus shown in fig. 1, in this embodiment, the fiber grating sensing and demodulating apparatus includes a C-band tunable laser 1, a fiber circulator 2, and a splitting ratio of 50: 50, a first optical fiber coupler 3, a first optical polarization controller 4, an optical fiber ring-down ring 5, an asymmetrically inserted acousto-optic modulator 6, an acousto-optic modulator driving source 7 with a sweep range of 90-110MHz, a balanced detector 8 with 1MHz, a 100KHz data acquisition card 9 and a computer 10, wherein in the embodiment, the computer 10 not only can be used as a storage unit of acquired data, but also can be used for processing the acquired data (for example, implanting a Labview program) by implanting data processing software, and can also be used for sending an instruction to the acousto-optic modulator driving source 7 for control. The acousto-optic modulator drive source 7 serves as a drive source of the acousto-optic modulator 6. The optical fiber ring-down ring 5 is a closed ring formed by connecting a second optical fiber coupler 5-1, a delay optical fiber 5-2 about 55 meters long, a second light polarization controller 5-3, a third optical fiber coupler 5-4 and a fiber grating 5-5 in sequence. The ring length of the fiber ring-down ring 5 should be longer than the coherence length of the laser source, and in this embodiment, the total length of the fiber ring-down ring is about 60 meters. The first optical fiber coupler 3, the first optical polarization controller 4, the optical fiber ring-down ring 5 and the acoustic-optical modulator 6 constitute a frequency-shifting interferometric sagnac interferometric loop.
The utility model discloses in, the beam split ratio of second fiber coupler 5-1 and third fiber coupler 5-4 should equal, and is greater than 99: 1. in this embodiment, the second fiber coupler 5-1 and the third fiber coupler 5-4 are used with a splitting ratio of 99.5: 0.5. In the utility model, the reflectivity of the fiber grating is not more than 10%. In this embodiment, the fiber grating 5-5 employed has a reflectivity of 10%.
In this embodiment, the C-band tunable laser 1 is a Santec TSL-510C type tunable laser. The optical fiber circulator 2 is a three-port non-reciprocal optical fiber device, and referring to fig. 1, an optical signal is input from a first port (i.e., port (r) shown in fig. 1) of the optical fiber circulator, and can only be output from a second port (i.e., port (r) shown in fig. 1); when an optical signal is input from the second port, the optical signal can only be output from the third port (i.e. the port (c) shown in fig. 1), and the optical fiber circulator plays a role in non-reversible transmission of light. The first optical Fiber coupler 3, the second optical Fiber coupler 5-1 and the third optical Fiber coupler 5-4 are all optical Fiber couplers of MC Fiber Optics company; the delay optical fiber 5-2 adopts YOFC optical fiber; the first optical polarization controller 4 and the second optical polarization controller 5-3 both use single mode fibers of MC Fiber Optics; the acousto-optic modulator 6 adopts a Brimrose AMM-100-20-25-1550-2FP model acousto-optic modulator; the acousto-optic modulator driving source 7 adopts a VFF-100-20-SPF-A-C2-X type driving source; the balance detector 8 adopts a new Focus model 2117; the data acquisition card 9 adopts an NI USB-6361 DAQ module.
Referring to fig. 2, a schematic diagram of the position relationship between the laser wavelength and the transmission spectrum of the fiber grating is shown. By adjusting the wavelength of the C-band tunable laser in this embodiment, the continuous wavelength of light emitted by the C-band tunable laser is located in the linear operating region I of the fiber grating 5-5, or the emitted continuous wavelength of light is located in the linear operating region II of the fiber grating 5-5 by adjustment. When the external parameters change, the transmission spectrum of the fiber grating moves integrally, and the transmission intensity changes linearly along with the external parameters, so that the additional loss introduced by the fiber grating also changes linearly. Based on this, can with the utility model discloses the device is applied to and measures the external parameter that fiber grating locates.
In this embodiment, the C-band tunable laser 1 is adjusted to emit a continuous laser wavelength in the linear working region of the fiber grating 5-5. Continuous laser emitted by the C-band tunable laser 1 enters a frequency-shifting interference Sagnac interference ring through a port II of the optical fiber circulator 2 and is divided into two beams of light with equal light intensity transmitted in clockwise and anticlockwise directions at the first optical fiber coupler 3. Light propagating clockwise is output to the first light polarization controller 4 from an output port of the first optical fiber coupler 3, enters the optical fiber ring-down ring 5 from a port of the second optical fiber coupler 5-1 for cyclic attenuation, 99.5% of light in each ring is left in the optical fiber ring-down ring 5 for continuous circulation, and only 0.5% of light leaks from the third optical fiber coupler 5-4 and reaches the first optical fiber coupler 3 after being frequency shifted by the acousto-optic modulator 6. Light transmitted in the anticlockwise direction is output to the acousto-optic modulator 6 from an output port of the first optical fiber coupler 3, enters the optical fiber ring-down ring 5 from a port of the third optical fiber coupler 5-4 for internal circulation and attenuation, and similarly, only 0.5% of light in each ring is leaked from the second optical fiber coupler 5-1 and returns to the first optical fiber coupler 3 through the first optical polarization controller 4. In the present invention, the first light polarization controller 4 and the second light polarization controller 5-3 are all used to adjust the polarization state of the light beam and to improve the visibility of the interference fringes.
In the fiber ring-down ring, the frequency of the reflected light of the fiber grating 5-5 is different from the frequency of the transmitted light of the backward incident fiber grating 5-5, one is the frequency of the original light source, and the other is the frequency of the frequency-shifted light, so that the transmitted light of the backward incident fiber grating 5-5 is not interfered. The reflected light does not influence the transmitted light with the same frequency and can not be simultaneously transmitted, because the light intensity of the reflected light is reduced to the original (0.5 percent) after the reflected light passes through the optical fiber coupler with the splitting ratio of 99.5:0.52The effect on the incident optical power of the fiber ring down loop is negligible and the lower the reflectivity of the fiber grating 5-5 (e.g., 1% or 0.1%), the more negligible this effect.
When the coherent length of the light source is shorter than the ring length of the fiber ring down ring, two beams of light with different ring numbers of ring-down in opposite directions do not interfere. In this embodiment, the coherence length of the light source is about 2.4 m, which is much shorter than the optical fiber ring-down ring of about 60 m, so that two beams of light with different ring numbers do not interfere in opposite directions, but two beams of light with the same ring number generate a constant phase difference due to different frequency shift positions, and thus interfere at the first optical fiber coupler 3. Then, the first optical fiber coupler 3 equally divides the light into two beams of light with equal light intensity, and the two beams of light enter the balance detector 8, specifically, the first beam of light enters the balance detector 8 through a port on the left side of the first optical fiber coupler 3; the second beam of light enters a port II of the optical fiber circulator 2 and then enters a balance detector 8 from the port III of the optical fiber circulator 2, and the balance detector 8 converts the optical signal into an electric signal after differential detection. The data acquisition card 9 acquires the electric signal data output by the balance detector 8 and then transmits the electric signal data to the computer 10.
The utility model discloses in, when the external parameter that fiber grating located changes, fiber grating transmission intensity can take place linear variation thereupon to lead to optic fibre to ring down the total loss of ring and ring down the distance and change, and handle through the signal of telecommunication data to transmit to computer 10 and can obtain ring down the distance. Therefore, the utility model discloses the device can be applied to and acquire the external parameter that fiber grating located.
The acquired electric signal data can be processed by implanting a Labview program in a computer. Performing fast Fourier transform on the electric signal data by using a Labview program to obtain a signal with amplitude attenuated along with the propagation distance, namely a spatial domain ring-down signal; and extracting the peak value of the space domain ring-down signal and fitting the peak value to obtain the ring-down distance of the optical fiber ring-down ring. Based on the ring-down distance, the external parameter or the change of the external parameter can be detected.
Although specific terms are employed herein for the purpose of describing the present invention in detail, it is to be understood that the scope of the present invention is not limited thereto, and that modifications and variations may be made by those skilled in the art without departing from the spirit and the principles of the present invention to achieve the same purpose.
Claims (6)
1. Fiber grating sensing demodulation device based on frequency shift interference fiber ring-down, characterized by:
the device comprises a C-band tunable laser, an optical fiber circulator and a light splitting ratio of 50: 50 of a first optical fiber coupler, a first light polarization controller, an optical fiber ring-down ring, an asymmetrically inserted acousto-optic modulator, an acousto-optic modulator driving source, a balance detector, a data acquisition card and a computer;
the optical fiber ring-down ring is a closed ring formed by sequentially connecting a second optical fiber coupler, a delay optical fiber, a second light polarization controller, a third optical fiber coupler and an optical fiber grating; the second optical fiber coupler and the third optical fiber coupler have the same splitting ratio, and the splitting ratio is not less than 99: 1; the reflectivity of the fiber grating is not more than 10%;
the output end of the C-band tunable laser is connected with a first port of the optical fiber circulator, a second port of the optical fiber circulator is connected with a first input port of the first optical fiber coupler, and a third port of the optical fiber circulator is connected with the balance detector; the second input port of the first optical fiber coupler is connected with the balance detector;
the first output port of the first optical fiber coupler is connected with the first optical polarization controller, and the second output port of the first optical fiber coupler is connected with the acousto-optic modulator; the first optical polarization controller is connected with an input port of the second optical fiber coupler in the optical fiber ring-down ring, and the acousto-optic modulator is connected with an input port of the third optical fiber coupler in the optical fiber ring-down ring;
the output end of the balance detector is connected with the data acquisition card; one end of the acousto-optic modulator driving source is connected with the acousto-optic modulator, the other end of the acousto-optic modulator driving source is connected with the computer, and the data acquisition card is connected with the computer.
2. The fiber grating sensing and demodulating apparatus based on frequency-shifting interferometric fiber ring-down of claim 1, wherein:
the C-band tunable laser is a Santec TSL-510C type tunable laser.
3. The fiber grating sensing and demodulating apparatus based on frequency-shifting interferometric fiber ring-down of claim 1, wherein:
the acousto-optic modulator adopts a Brimrose AMM-100-20-25-1550-2FP model acousto-optic modulator.
4. The fiber grating sensing and demodulating apparatus based on frequency-shifting interferometric fiber ring-down of claim 1, wherein:
the acousto-optic modulator driving source adopts a VFF-100-20-SPF-A-C2-X type driving source.
5. The fiber grating sensing and demodulating apparatus based on frequency-shifting interferometric fiber ring-down of claim 1, wherein:
the balanced detector employs a new fox model 2117.
6. The fiber grating sensing and demodulating apparatus based on frequency-shifting interferometric fiber ring-down of claim 1, wherein:
the data acquisition card adopts an NI USB-6361 DAQ module.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202020859790.XU CN212300381U (en) | 2020-05-21 | 2020-05-21 | Fiber grating sensing demodulation device based on frequency shift interference fiber ring-down |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202020859790.XU CN212300381U (en) | 2020-05-21 | 2020-05-21 | Fiber grating sensing demodulation device based on frequency shift interference fiber ring-down |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN212300381U true CN212300381U (en) | 2021-01-05 |
Family
ID=73967537
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202020859790.XU Active CN212300381U (en) | 2020-05-21 | 2020-05-21 | Fiber grating sensing demodulation device based on frequency shift interference fiber ring-down |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN212300381U (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114199290A (en) * | 2021-12-15 | 2022-03-18 | 湖北工业大学 | Airspace active optical fiber cavity ring-down sensing device and sensing method |
-
2020
- 2020-05-21 CN CN202020859790.XU patent/CN212300381U/en active Active
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114199290A (en) * | 2021-12-15 | 2022-03-18 | 湖北工业大学 | Airspace active optical fiber cavity ring-down sensing device and sensing method |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN102279095B (en) | Device for reducing influence of birefringent chromatic dispersion on polarization coupling measurement of polarization maintaining optical fiber | |
| CN107894245B (en) | Polarization-maintaining optical fiber interferometer capable of simultaneously measuring strain and temperature | |
| CN101592551B (en) | Sagnac interferometer-based method and Sagnac interferometer-based device for testing beat length of polarization maintaining optical fiber | |
| CN103900797B (en) | With the optical coherence territory polarimeter of light path scanning position and velocity correction | |
| CN102288388B (en) | Device and method for improving polarization-maintaining optical fiber polarization coupling measurement precision and symmetry | |
| CN108827601A (en) | A kind of measuring device of fibre optic interferometer arm length difference | |
| CN102607621A (en) | Distributed optical fiber Brillouin sensing device and method thereof for detecting temperature and strain synchronously | |
| CN103900798B (en) | A kind of optical coherence domain polarization measurement device scanning on-line correction with light path | |
| CN101319878B (en) | Method and device for high-precision large-range measuring size of optical fiber | |
| CN105784336B (en) | A kind of transmission of optical fibre device and reflecting properties test device and method | |
| CN109959403B (en) | Multi-parameter large-capacity sensing system | |
| CN110132330B (en) | Double refraction distributed measuring system and method based on CP-phi OTDR | |
| EP3066423B1 (en) | Single-end brillouin optical distributed sensing device and method | |
| CN105973450A (en) | Optical fiber Fizeau interferometric array distributed vibration sensing system and method | |
| CN103674497A (en) | High accuracy measurement system of line width of narrow line width laser | |
| CN108007603B (en) | Multi-parameter distribution measuring system based on asymmetric double-core optical fiber | |
| CN113804299A (en) | Optical fiber device distributed bidirectional polarization measuring device based on optical frequency domain interference | |
| CN108844717A (en) | A kind of measurement method of fibre optic interferometer arm length difference | |
| CN105628174A (en) | Optical fiber F-P sensor vibration demodulation system based on polarization switching | |
| CN212300381U (en) | Fiber grating sensing demodulation device based on frequency shift interference fiber ring-down | |
| CN111896036B (en) | Demodulation method of continuous wave space domain fiber grating cavity ring-down sensor system | |
| CN106770029A (en) | A kind of face type optic fibre refractive index sensor array measurement system and method | |
| CN107976300B (en) | Method for measuring beat length of polarization maintaining optical fiber | |
| CN107356412B (en) | A kind of measurement method of the measuring system based on rare-earth doped optical fibre refractive index | |
| CN113804412A (en) | Optical fiber device micro-chromaticity dispersion measuring device based on ring light path structure |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| GR01 | Patent grant | ||
| GR01 | Patent grant |